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Date: Thu, 17 Jun 2010 20:44:32 +0300 (EEST)
Subject: Cassandra Multiple DataCenter Suitability - why?
From: altanis@ceid.upatras.gr
To: dev@cassandra.apache.org
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Hello,

I keep reading everywhere that Cassandra has supported multiple
datacenters from the beginning. I would like to know what does Cassandra
do to achieve that. Is it just that the developers have written some code
that supports that scenario, or is there something inherent in Cassandra's
design that is suitable for a multi DC environment, like minimizing
inter-DC traffic?

I have read about RackAwareStrategy on the wiki, and have also browsed
through some code (DataCenterShardStrategy), but I would like to see what
people have to say about this.

I also read about an implemenetation of Rack Awareness employing
Zookeeper, but I gather that wasn't released by Facebook and it was more
geared towards single-DC rack awareness because Zookeeper is a bit heavy
on the bandwidth.

Anyway, just to sum it up, my question is this: please explain in brief
the reasons why Cassandra is well suited for multi-DC environments.

Alexander Altanis